Biomedical subjects

Graham Sandford

Publications and source records attributed to Graham Sandford.

6 recordsLinked to original sources

PubMed2005

Polyfunctional tetrahydropyrido[2,3-b]pyrazine scaffolds from 4-phenylsulfonyl tetrafluoropyridine.

[Reaction: see text]. Polyfunctional tetrahydropyrido[2,3-b]pyrazine scaffolds can be synthesized by sequential reaction of pentafluoropyridine with sodium phenylsulfinate and an appropriate diamine. The polyfunctionality possessed by the difluorinated tetrahydropyrido[2,3-b]pyrazine scaffolds was demonstrated in selected model reactions with nucleophiles to give access to various polysubstituted [6,6]-ring fused systems.

Molecular Structure↗

PubMed2005

Tetrahydropyrido[3,4-b]pyrazine scaffolds from pentafluoropyridine.

[reaction: see text] Representative polyfunctional tetrahydropyrido[3,4-b]pyrazine scaffolds have been synthesized very readily by a one-pot annelation reaction of pentafluoropyridine with appropriate diamines. The trifluorinated pyridopyrazine products react sequentially with various nucleophiles to give poly-substituted tetrahydropyridopyrazines, demonstrating the potential of the polyfluorinated ring fused pyridine system as a scaffold for the synthesis of previously inaccessible poly-substituted pyridopyrazine derivatives. This general approach has special relevance to the development of new chemical entities for the life science industries and particularly in the drug discovery arena, in which low molecular weight, polyfunctional heterocyclic derivatives are playing an increasingly important role.

Pyrazines↗

PubMed2005

Elemental fluorine. Part 18. Selective direct fluorination of 1,3-ketoesters and 1,3-diketones using gas/liquid microreactor technology.

1,3-Ketoesters and 1,3-diketones react with fluorine gas, using Durham multichannel modular microreactor technology, on a preparatively useful scale. High conversions and yields of monofluorinated products were obtained. A consideration of the mechanism of fluorination of dicarbonyl systems provides a rationale of the scope and limitations of the use of microreactor technology for such direct fluorination processes. We conclude that it is especially appropriate for the fluorination of diketones and ketoesters that exist mainly in the enol form at equilibrium and/or undergo rapid keto-enol interconversion. A one-stage route to fluoroketones from ketoesters was achieved by allowing the crude product mixture obtained from the fluorination of the ketoesters to stand for a period of time before reaction work-up.

Biotechnology↗

PubMed2005

Elemental fluorine. Part 16. Versatile thin-film gas-liquid multi-channel microreactors for effective scale-out.

Versatile and conveniently operated microreactor devices, suitable for long term chemical synthesis for both laboratory and industrial use, are described. Direct fluorination of ethyl acetoacetate by fluorine gas is used as a model reaction to illustrate the successful application of reactors having either 9, 18 or 30 microchannels, with all channels supplied from single reagent sources, to provide significant quantities of fluorinated products. Convenient reactor maintenance, simple design, versatility and the enhanced safety features of using such modular microreactor devices, make these systems appropriate for synthesis on the large scale.

Journal Article↗

PubMed2003

Polyhalogenated heterocyclic compounds. Macrocycles from perfluoro-4-isopropylpyridine.

Perfluoro-4-isopropylpyridine was used as a building block for the two-step synthesis of a variety of macrocyclic systems bearing pyridine sub-units which were characterised by X-ray crystallography. Electrospray mass spectrometry revealed that complexation of either cations and, unusually, anions is possible depending on the structure of the macrocycle.

Anions↗

PubMed2003

Macrocycles from perhalogenated heterocycles.

Perhalogenated heteroaromatic systems, such as trichloro-s-triazine and pentafluoropyridine, are multifunctional "building blocks" that react with a number of appropriate difunctional nucleophiles to provide access to a variety of macrocyclic and even cage-like molecular architectures. Unusual structural and complexation characteristics of the systems reported so far, such as the recognition of anions, provide a further stimulus for the development of this area.

Bridged-Ring Compounds↗